In rock drilling and rock bolting, one often uses a rock drilling rig where one or more drilling machines are carried by respective movable arms, or booms. The booms are usually flexibly attached to a carrier, such as a vehicle, via one or more joints. Furthermore, the drilling machine is usually flexibly attached to the end of the boom away from the carrier via one or more additional joints.
The drilling machine is usually not attached directly to the boom, instead being normally attached to the boom displaceable by a feed unit, for example, consisting of a feeder holder, which carries a feed beam arranged movably relative to the feeder holder, and furthermore the drilling machine is usually movable relative to the feed beam to achieve great freedom of adjustment during drilling thanks to the telescopic action, without the carrier having to move around.
Depending on the type of drilling, such as tunnelling or ore mining, different types of rock drilling rigs are used. For example, when driving a tunnel, one often uses large machines with a plurality of booms, so as to drill a plurality of holes at the same time, or nearly so, while in ore mining, for example, it is often desirable for economic reasons to mine the ore in such a way that only the ore body is mined, thereby reducing as much as possible the amount of excess rock that needs to be handled.
Whether it involves tunnelling or ore mining, it is often necessary to reinforce the rock surfaces exposed by blasting in order to lessen the risk of a cave-in. This reinforcing is often done by first boring a hole and then placing a rock reinforcement bolt in the hole.
This rock reinforcement is usually done by a combined rock drilling and bolting rig, where the same rig first drills the hole and then installs the bolt. In some applications, the very same rig can be used both to drill the blast holes needed for the ore mining/tunnel driving and for subsequent rock reinforcement by installing bolts.
In certain fields of application, such as mining of narrow ore bodies, mining can take place with very low and/or narrow galleries, which places special demands on the rock drilling rig. For example, not only does the desired function need to be assured, but also the existing design constraints must be fulfilled. Rock bolting is often done with bolts over 1 meter in length, and when a rock drilling rig is used for bolting in low/narrow galleries it can be hard to produce a feed unit that enables bolting with the required bolt length without needing complex adjustments of the supporting unit and/or feed unit.
U.S. Pat. No. 7,032,686 B2 shows a rock drilling and bolting rig designed to be used in mines with low gallery height. The rig shown can be used to drill a bolt hole and then install a rock bolt in the borehole. The drilling machine and bolt holder are arranged along a common circular periphery, and when switching between drilling and bolting the layout rotates about the axis of the circle.
Still, there is a need for an improved rock drilling rig to be used in both drilling and bolting, especially for rock drilling rigs designed for very narrow galleries.